Time-based plane separation to cut Heathrow delays

By Lorna Sharpe

Published Monday, February 17, 2014

Heathrow will be the first airport in the world to manage arriving flights by time separation instead of distance.

Air traffic control firm Nats says the procedure will radically cut delays and reduce cancellations due to high winds. It will be introduced from spring 2015. Traditionally, flights are separated by set distances dependent on the type of aircraft and the size of the spiralling turbulence – or wake vortex – they create as they fly.

Heathrow has been operating at 98 per cent of its runway capacity for a decade. Normally a flight takes off or lands every 45 seconds.

In strong headwinds, aircraft fly more slowly over the ground, so maintaining a set separation distance in those conditions reduces the landing rate and can have a significant knock-on effect on airport capacity, causing delays and cancellations.

The introduction of a time-based separation method will help maintain the landing rate and save more than 1,300 hours of delay every year – halving the current delay figure while reducing the need for airlines to cancel flights due to the effects of strong headwinds.

Martin Rolfe, Nats managing director operations, said: “The introduction of time-based separation at Heathrow will be a world first and deliver major benefits for our customers – both Heathrow Airport and the airlines.”

Supported in the Airports Commission’s interim report in December 2013, the delivery of time-based separation comes after three years of exhaustive analysis. Nats studied over 100,000 flights using state-of-the-art equipment to accurately measure the behaviour of aircraft wake vortices in strong headwinds.

The results show that they dissipate more quickly in windy conditions, therefore allowing aircraft to be closer together on final approach while maintaining safety as the main priority.